This script allows multiple image selections to appear and scroll down the entire page by criss crossing each other style. This could be used for many presentations and products and look really cool if you are creative. 

Insert this code into your BODY of HTML

<script language="JavaScript1.2" type="text/javascript"> //This Code Free To Use - Providing This Notice Remains// //Autumn leaves- by Kurt Grigg (kurt.grigg@virgin.net)// //Modified by Dynamic Drive for NS6 functionality// //visit http://www.dynamicdrive.com for this script// //JavaScript Code Effect Found At: Development Resource & JavaScript Code & Generator Public Archive Center// //Located: http://www.DesignerWiz.com// //Though This Material May Have Been In A Public Depository, Certain Author Copyright Restrictions May Apply*// //Pre-load your image below! grphcs=new Array(6) Image0=new Image(); Image0.src=grphcs[0]="../images/pic1.gif"; Image1=new Image(); Image1.src=grphcs[1]="../images/pic2.gif" Image2=new Image(); Image2.src=grphcs[2]="../images/pic3.gif" Image3=new Image(); Image3.src=grphcs[3]="../images/pic4.gif" Image4=new Image(); Image4.src=grphcs[4]="../images/pic5.gif" Image5=new Image(); Image5.src=grphcs[5]="../images/pic6.gif" Amount=8; //Smoothness depends on image file size, the smaller the size the more you can use! Ypos=new Array(); Xpos=new Array(); Speed=new Array(); Step=new Array(); Cstep=new Array(); ns=(document.layers)?1:0; ns6=(document.getElementById&&!document.all)?1:0; if (ns){ for (i = 0; i < Amount; i++){ var P=Math.floor(Math.random()*grphcs.length); rndPic=grphcs[P]; document.write("<LAYER NAME='sn"+i+"' LEFT=0 TOP=0><img src="+rndPic+"></LAYER>"); } } else{ document.write('<div style="position:absolute;top:0px;left:0px"><div style="position:relative">'); for (i = 0; i < Amount; i++){ var P=Math.floor(Math.random()*grphcs.length); rndPic=grphcs[P]; document.write('<img id="si'+i+'" src="'+rndPic+'" style="position:absolute;top:0px;left:0px">'); } document.write('</div></div>'); } WinHeight=(ns||ns6)?window.innerHeight:window.document.body.clientHeight; WinWidth=(ns||ns6)?window.innerWidth-70:window.document.body.clientWidth; for (i=0; i < Amount; i++){ Ypos[i] = Math.round(Math.random()*WinHeight); Xpos[i] = Math.round(Math.random()*WinWidth); Speed[i]= Math.random()*5+3; Cstep[i]=0; Step[i]=Math.random()*0.1+0.05; } function fall(){ var WinHeight=(ns||ns6)?window.innerHeight:window.document.body.clientHeight; var WinWidth=(ns||ns6)?window.innerWidth-70:window.document.body.clientWidth; var hscrll=(ns||ns6)?window.pageYOffset:document.body.scrollTop; var wscrll=(ns||ns6)?window.pageXOffset:document.body.scrollLeft; for (i=0; i < Amount; i++){ sy = Speed[i]*Math.sin(90*Math.PI/180); sx = Speed[i]*Math.cos(Cstep[i]); Ypos[i]+=sy; Xpos[i]+=sx; if (Ypos[i] > WinHeight){ Ypos[i]=-60; Xpos[i]=Math.round(Math.random()*WinWidth); Speed[i]=Math.random()*5+3; } if (ns){ document.layers['sn'+i].left=Xpos[i]; document.layers['sn'+i].top=Ypos[i]+hscrll; } else if (ns6){ document.getElementById("si"+i).style.left=Math.min(WinWidth,Xpos[i]); document.getElementById("si"+i).style.top=Ypos[i]+hscrll; } else{ eval("document.all.si"+i).style.left=Xpos[i]; eval("document.all.si"+i).style.top=Ypos[i]+hscrll; } Cstep[i]+=Step[i]; } setTimeout('fall()',20); } window.onload=fall //--> </script>

Simply Cut and Paste Script code
Be sure to properly place script position in Body section of html
You may see a working example of this cool code here
You also have control of the speed of effect

Credit: Roberto de Jesus Asyn Diaz Homepage

This script has been in the DesignerWiz.com Public Library.